Laryngoscopy is an endoscopy of the larynx, a part of the throat. A laryngoscope is a hand held medical instrument used for visual examination of the larynx and trachea of a patient during a laryngoscopy. It is a medical procedure that is used to obtain a view, for example, of the vocal folds and the glottis. The instrument appears in two basic forms, an indirect laryngoscope and a direct laryngoscope. The indirect form utilizes a mirror held near the back of the pharynx while a light is directed upon it from a reflector worn on the forehead of the examiner. This is usually performed in the office setting. The second type, a direct laryngoscope, is equipped with a built in illuminating device and a blade. Direct laryngoscopy may be performed to facilitate tracheal intubation during general anaesthesia or cardiopulmonary resuscitation or for surgical procedures on the larynx or other parts of the upper tracheobronchial tree. Direct laryngoscopy is carried out (usually) with the patient lying on his or her back; the laryngoscope is inserted into the mouth and the tongue is moved out of the line of sight. Depending on the type of blade (a projecting structure of the laryngoscope to move the epiglottis and tongue forward to provide an unobstructed view of the larynx and trachea) used, the laryngoscope is inserted either anterior or posterior to the epiglottis and then lifted with an upwards and forward motion (“away from you and towards the roof of the mouth”). This move makes a view of the glottis possible. This procedure can be done in an operation theatre with full preparation for resuscitative measures to deal with respiratory distress. Video laryngoscopes are currently available, and they employ a variety of features such as a monitor on the handle and or channels to assist in guiding the endotracheal tube into the trachea.
Intraoperative CT (computed tomography) and MR (magnetic resonance) imaging affords the opportunity to study the soft tissue deformation that occurs as a result of instrumentation of the upper aerodigestive tract during operative laryngoscopy and other trans-oral surgical procedures. Transoral surgery (TOS) has revolutionized management of tumors of the pharynx and larynx. Intraoperative surgical navigation may play a role in assessing tumor extent and avoidance of critical structures in TOS but has not been studied. Unlike the case with imaging acquired for sinus and skull base surgery, the upper aerodigestive tract anatomy changes once the patient undergoes general anesthesia and during suspension laryngoscopy, thus rendering preoperative imaging unusable. A better understanding of how the upper aerodigestive tract deforms during instrumentation is critical in areas such as airway management during intubation and trans-oral resection of benign and malignant tumors of the upper aerodigestive tract. Intraoperative imaging such as CT or MRI would allow for improved visualization and understanding of this upper aerodigestive tract deformation. However, intraoperative images acquired during surgery of the upper aerodigestive tract can be partially obscured by images and reflections of the laryngoscope itself (called “artifacts”) because the TOS instrumentation, including laryngoscopy devices and other surgical retractors, is made of stainless steel and is contraindicated in MR and CT imaging. This is distinct disadvantage of the conventional metal laryngoscopes. A further disadvantage is that conventional laryngoscopes are mounted on the thorax of the patient, such that the respiration of that individual can cause the laryngoscope to rise and fall, creating motion-induced distortions and inaccuracies in the imaging itself.
It would be desirable to have a laryngoscope that is compatible with these imaging systems, does not rest on the patient's body, and to provide a device that is potentially customized to the anatomical specificities of an individual patient's anatomy.